It rather depends upon the arrangement of the serial and parallel components.
If there's a lot of parallel components as compared to the serial than it may be less work to do the parallel combination first.
Conversely if there's more serial components then doing the serial first may work better.
You rather have to look at the circuit and think about which order of solution requires fewer calculations.

Since we aren't mind readers, we have no idea what "this circuit" looks like. This is like saying that you have a car that needs repair and asking if you should open the hood or trunk first. The question has no meaningful context.